The problem I have is that the output from the SDFM module is wrong sometimes. In the oscilloscope shot below:
- CH1 (yellow) is a +/-10V input (via resistor divider) to the AMC1303E2510 chip for Filter 1. +/-10V produces +/-250mV at the AMC1303E2510 input.
- CH2 (pink) is the DAC output for Filter 1 (note that it is passed through an external op-amp buffer to increase it's amplitude).
At first I thought it was a problem with the MCU SDFM, however now I'm wondering if I am exceeding the valid input range of the AMC1303E2510 chip. In the oscilloscope shot below the input is +/-10V which produces +/-250mV at the AMC1303E2510 input. From the datasheet the AMC1303E2510 the full input range is +/-320mV, however linear operation is only guaranteed for +/-250mV. So perhaps the input is just exceeding +/-250mV when one of these incorrect readings occurs.
When I reduced the input to +/-9V (+/-225mV at the AMC1303E2510 input) the behaviour is good (i.e. no spurious/incorrect results).
Can you provide more info on the expected behaviour when the AMC1303E2510 input is between 250mV and 320mV? Can the data be completely corrupted as in the shot below?